Redistribution layers including reinforcement structures and related semiconductor device packages, systems and methods

ABSTRACT

Embodiments of a redistribution layer structure comprise a low-k dielectric material and incorporating a reinforcement structure proximate and inward of a peripheral edge thereof, the reinforcement structure comprising conductive material electrically isolated from conductive paths through the RDL structure. Semiconductor packages including an embodiment of the RDL structure and methods of fabricating such RDL structures are also disclosed.

TECHNICAL FIELD

Embodiments disclosed herein relate to redistribution layer (RDL) structures for use with semiconductor dice. More particularly, embodiments disclosed herein relate to RDL structures including structural reinforcements to prevent or at least reduce potential for degradation of the RDL structure during processing, handling and operation, to semiconductor device packages and systems including such RDL structures and methods of forming RDL structures including structural reinforcements.

BACKGROUND

It has become increasingly common to employ redistribution layer (RDL) structures with semiconductor dice to reroute power, ground/bias and signal connections from bond pads of a die to a rearranged pattern of external connections, generally with a greater pitch (i.e., spacing) between the external connections of the RDL structure in comparison to the pitch between bond pads of the die. An RDL structure may comprise a single level of conductive traces between two layers of a dielectric material, the traces coupled to an associated semiconductor die through contacts extending from the encapsulated traces to an exposed surface of one dielectric layer and optionally to surface traces, and to higher-level packaging through contacts extending from the traces to external connections in the form of bumps, pillars, balls or studs on an exposed surface of the other dielectric layer. Of course, as complexity of semiconductor dice has increased while, at the same time overall dimensions of dice as well as critical dimensions of features of integrated circuitry of dice have decreased, it has become desirable to fabricate RDL structures with multiple levels of traces, interposed dielectric layers, and interlayer contacts.

One particular application of RDL structures is in fabrication of a so-called “fan-out wafer level package” (FOWLP), where lateral dimensions of the RDL structure extend substantially beyond the periphery of a die to which the RDL structure is secured and operably coupled to provide an array of external connections at a substantially greater pitch than that of the bond pads of an associated semiconductor die. The term “wafer level” is indicative of the fact that some such packages are formed conventionally on a large array of preformed RDL structures or, alternatively, that the RDL structures are formed on a large array of laterally-spaced semiconductor dice. The present and continued scaling, also characterized as miniaturization, of integrated circuitry and, concurrently, semiconductor devices, and associated thinning of dielectric materials, has reached a point where charge buildup and cross-talk may adversely affect performance of a semiconductor device. Thus, in current state of the art FOW RDL structures, it is desirable to employ so-called “low-k” dielectric materials, wherein k is a dielectric constant. A low-k dielectric material may be generalized as a material with a small dielectric constant relative to the dielectric constant k, of 3.9, of SiO₂, silicon dioxide. More specifically, a low-k dielectric material may be said to exhibit a dielectric constant k of <3. Utilization of low-k dielectrics enhances radiofrequency performance through reduction in parasitic capacitance, and allowing faster switching speeds, as well as facilitating heat dissipation.

Low-k dielectric materials suitable for use in RDL structures generally comprise polymeric dielectrics, due in large part to the ability to deposit the material using techniques developed for photoresist application, such as spin-on and spray-on techniques, as well as dry film lamination. Examples of organic low-k polymeric dielectrics include without limitation polyimides, polynorborenes, benzcyclobutene (BCB) and polytetrafluoroethylene (PTFE). Examples of silicon-based low-k polymeric dielectrics include hydrogen silsesquioxane (HSQ) and methylsilsesquioxane (MSQ).

While addressing the problems noted above, such polymeric low-k dielectrics suffer from low mechanical strength and thermal stability, resulting in enhanced potential for dielectric layer cracking and delamination than is present with previous conventional silicon or ceramic-based interposer technology, or the use of more physically robust polymer dielectrics in an RDL structure. The substantial lateral extension of the RDL structure beyond the periphery of an associated semiconductor die in a FOWLP results in a number of structural integrity issues. For example, mismatch of a coefficient of thermal expansion (CTE) of various components of a FOWLP, for example the semiconductor die employed in the package, the low-k dielectric and the conductive traces and contacts of the RDL structure, as well as a molding compound encapsulating the die and in contact with the RDL structure induce stress in the package. Further, residual stresses in the FOWLP due to cooling of the molding compound during cure and while adhered to the relatively flexible RDL structure may stress the laminated RDL structure, causing cracking or even delamination. Thermal cycling events such as the encapsulation process with heated molding compound, thermocompression bonding of semiconductor die bond pads to contact pads on the RDL structure, solder reflow of conductive bumps formed on the RDL structure as well as drastic cyclical temperature changes, for example, from about 125° C. to about −40° C. to about −50° C. during package qualification as well as less severe but repeated and protracted thermal cycling during operation of the packaged semiconductor die, may be highly destructive to integrity of the RDL structure and to the FOWLP. Thus, thermal and mechanical stresses applied to RDL structures during fabrication, handling and operation of a completed semiconductor device package employing low-k dielectric materials in an RDL structure may exhibit both increased infant mortality as well as an unacceptably short operational life.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic side sectional elevation of a conventional FOWLP;

FIG. 1A is an enlarged portion of the right-hand side of FIG. 1 schematically indicating potential crack propagation paths through the FOWLP;

FIG. 2 is an enlarged schematic side sectional elevation of one embodiment of an RDL structure according to the disclosure;

FIG. 2A is an enlarged schematic sectional elevation transverse to FIG. 2 and taken across section line A-A thereof, illustrating one implementation of the embodiment of FIG. 2;

FIG. 2B is an enlarged schematic sectional elevation transverse to FIG. 2 and taken across section line A-A thereof, illustrating another implementation of the embodiment of FIG. 2;

FIG. 3A is a schematic top elevation of another embodiment of an RDL structure according to the disclosure;

FIG. 3B is an enlarged schematic sectional elevation of a peripheral portion of the RDL structure of FIG. 3A taken across section line B-B of FIG. 3A, perpendicular to a major plane of the RDL structure and perpendicular to an adjacent peripheral edge of the RDL structure;

FIG. 3C is a schematic top elevation of another implementation of the embodiment of FIG. 3A; and

FIG. 3D is a schematic top elevation of a further implementation of the embodiment of FIG. 3A.

Due to the nature of the structures illustrated in the drawing figures and described in the specification, section lines indicating different materials have been omitted from the drawings intentionally for clarity.

DETAILED DESCRIPTION

RDL structures are described herein as including peripheral reinforcement structures, such reinforcement structures being fabricated simultaneously with the traces, contacts and other conductive elements of the RDL structure and without the necessity of using different and additional materials or process acts.

The following description provides specific details, such as sizes, shapes, material compositions, and orientations in order to provide a thorough description of embodiments of the disclosure. However, a person of ordinary skill in the art would understand that the embodiments of the disclosure may be practiced without necessarily employing these specific details. Embodiments of the disclosure may be practiced in conjunction with conventional fabrication techniques employed in the industry. In addition, the description provided below does not form a complete process flow for manufacturing a reinforcement structure for an RDL structure, and RDL structure including a reinforcement structure, or an apparatus (e.g., semiconductor device, semiconductor device package, etc.) including an RDL structure incorporating a reinforcement structure according to an embodiment. Only those process acts and structures necessary to understand the embodiments of the disclosure are described in detail below. Additional acts to form a complete reinforcement structure, a complete RDL structure including a reinforcement structure, or a complete apparatus (e.g., a semiconductor device, a semiconductor device package, etc.) including a reinforcement structure from the structures described herein may be performed by conventional fabrication processes.

Drawings presented herein are for illustrative purposes only, and are not meant to be actual views of any particular material, component, structure, device, or system. Variations from the shapes depicted in the drawings as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein are not to be construed as being limited to the particular shapes or regions as illustrated, but include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as box-shaped may have rough and/or nonlinear features, and a region illustrated or described as round may include some rough and/or linear features. Moreover, sharp angles between surfaces that are illustrated may be rounded, and vice versa. Thus, the regions illustrated in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of a region and do not limit the scope of the present claims. The drawings are not necessarily to scale.

As used herein, the terms “comprising,” “including,” “containing,” “characterized by,” and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional, unrecited elements or method acts, but also include the more restrictive terms “consisting of” and “consisting essentially of” and grammatical equivalents thereof. As used herein, the term “may” with respect to a material, structure, feature or method act indicates that such is contemplated for use in implementation of an embodiment of the disclosure and such term is used in preference to the more restrictive term “is” so as to avoid any implication that other, compatible materials, structures, features and methods usable in combination therewith should or must be, excluded.

As used herein, the terms “longitudinal,” “vertical,” “lateral,” and “horizontal” are in reference to a major plane of a substrate (e.g., base material, base structure, base construction, etc.) in or on which one or more structures and/or features are formed and are not necessarily defined by Earth's gravitational field. A “lateral” or “horizontal” direction is a direction that is substantially parallel to the major plane of the substrate, while a “longitudinal” or “vertical” direction is a direction that is substantially perpendicular to the major plane of the substrate. The major plane of the substrate is defined by a surface of the substrate having a relatively large area compared to other surfaces of the substrate.

As used herein, spatially relative terms, such as “beneath,” “below,” “lower,” “bottom,” “above,” “over,” “upper,” “top,” “front,” “rear,” “left,” “right,” and the like, may be used for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Unless otherwise specified, the spatially relative terms are intended to encompass different orientations of the materials in addition to the orientation depicted in the figures. For example, if materials in the figures are inverted, elements described as “over” or “above” or “on” or “on top of” other elements or features would then be oriented “below” or “beneath” or “under” or “on bottom of” the other elements or features. Thus, the term “over” can encompass both an orientation of above and below, depending on the context in which the term is used, which will be evident to one of ordinary skill in the art, and does not necessarily require or indicate that a structure “over” another structure is in direct contact therewith. The materials may be otherwise oriented (e.g., rotated 90 degrees, inverted, flipped) and the spatially relative descriptors used herein interpreted accordingly.

As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

As used herein, the terms “configured” and “configuration” refer to a size, shape, material composition, orientation, and arrangement of one or more of at least one structure and at least one apparatus facilitating operation of one or more of the structure and the apparatus in a predetermined way.

As used herein, the term “substantially” in reference to a given parameter, property, or condition means and includes to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met with a degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90.0% met, at least 95.0% met, at least 99.0% met, or even at least 99.9% met.

As used herein, the term “about” in reference to a given parameter is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the given parameter).

As used herein the terms “layer” and “film” mean and include a level, sheet or coating of material residing on a structure, which level or coating may be continuous or discontinuous between portions of the material, and which may be conformal or non-conformal, unless otherwise indicated.

As used herein, the term “within proximity to” in reference to a location of a reinforcement structure of embodiments of the disclosure means and includes locations for the reinforcement structure suitable to prevent delamination of the RDL structure at a peripheral edge thereof, yet far enough inward of the peripheral edge so as to not be susceptible to electrical shorting at the peripheral edge.

In the accompanying drawing figures, like elements are identified by the same or similar reference numerals.

By way of relevant background, RDL structures including those suitable for use in a FOWLP, may be fabricated, layer by layer, using one of two techniques. In one instance, an array of RDL structures is formed on a panel, such as a glass panel or a wafer, by depositing and patterning a conductive layer, such as copper or aluminum, followed by depositing and patterning a polymeric dielectric material to form holes exposing portions of the patterned conductive layer, forming contacts in the holes by conductive material deposition simultaneously with forming conductive traces, followed by deposition and patterning of another dielectric layer until the desired number of trace levels is formed and conductive contact material is exposed on opposing sides of the RDL structure for connection, respectively, to bond pads of a semiconductor die and to conductive elements for connection to higher level packaging. The conductive material may be deposited by electroplating or electroless plating, and patterned using a patterned positive or negative tone photoresist followed by etching. The dielectric material may be applied by spin coating, spray coating or dry film lamination, again followed by pattering using a photoresist, followed by etching. Examples of organic low-k polymeric dielectrics include without limitation polyimides, polynorborenes, benzcyclobutene (BCB) and polytetrafluoroethylene (PTFE). Examples of silicon-based low-k polymeric dielectrics include hydrogen silsesquioxane (HSQ) and methylsilsesquioxane (MSQ). In one embodiment, the dielectric material may itself be a photodefinable dielectric material, for example a polyimide material incorporating so-called “photo pack” chemistry, and patterned using a partially transmissive photomask, commonly termed a “leaky chrome” reticle, to directly pattern the dielectric material, followed by contact with a developer solvent, and cure of the remaining dielectric material in a desired pattern. In another instance, the RDL structure may be formed on a preplaced array of semiconductor dice or wafer segments, and formed layer by layer on the dice or wafer segments as described above. The latter technique may be less suitable for FOWLP applications, as involving preplacement of laterally separated dice or wafer segments in a material matrix before RDL structure is formed.

FIG. 1 is a simplified schematic side sectional elevation of a conventional FOWLP 100 comprising a semiconductor die 102, an RDL structure 104 and a molding compound 106 encapsulating a back and sides of semiconductor die 102 and in contact with a major surface MS1 of RDL structure 104 extending peripherally beyond the footprint of semiconductor die 102. On a side of RDL structure 104 facing semiconductor die 102 (i.e., major surface MS1), bond pads 108 of semiconductor die 102 are operably coupled to contacts 110 of RDL structure 104, which are connected to conductive traces 112 and optionally through other interlayer contacts (see FIG. 1A) and other trace levels (see FIG. 1A), to contacts 110 on the opposing major surface MS2 of RDL structure 104 operably coupled to conductive elements 114 in the form of solder bumps on under bump metallization (UBM), the solder bumps having been reflowed and constrained to desired locations by patterned solder stop 116. The conductive traces 112 are electrically isolated above and below by a low-k dielectric material 118, through which contacts 110 extend.

RDL structure 104 may comprise a series of alternating multiple levels of conductive traces 112 and low-k dielectric material 118, as shown in more detail in FIG. 1A. Conductive traces 112 of multiple levels may be mutually connected by interlayer contacts 120, and provided with conductive paths to opposing sides of RDL structure 104 through contacts 110. Contacts 110 and 120 extend through holes in adjacent and surrounding levels of low-k dielectric material 118. Therefore, RDL structure 104 may be characterized as a laminate of conductive and dielectric materials, although the various levels of low-k dielectric material 118 become bonded to one another, and to conductive traces 112 as well as to contacts 110 and 120 during the RDL structure fabrication process. While the RDL structure 104 is, as noted above, relatively easy and economical to fabricate without the use of exotic materials and fabrication techniques, when low-k dielectric materials are employed for the dielectric levels, the somewhat fragile nature of these materials from a mechanical and thermal stress standpoint becomes an issue in terms of maintaining structural integrity of the RDL structure 104.

As indicated by arrows C₁ in FIG. 1A, due to mechanical (e.g., bending, shear, torsional) stress and thermal (e.g., elevated temperatures, temperature cycling between elevated and sub-ambient temperatures) stresses, as well as combinations of the foregoing, RDL structure 104 may crack as shown by broken lines by delamination of adjacent levels of low-k dielectric material 118 or through cracks in the low-k dielectric material 118 of a given level, potentially exposing conductive traces 112 to moisture and inducing shorts between adjacent conductive traces 112, or damaging conductive traces 112 or separation from interlayer contacts 120. In another aspect, a crack C₂ may form between molding compound 106 encapsulating semiconductor die 102 and RDL structure 104, damaging connections between bond pads 108 and contacts 110, and even extending into the active surface 122 of semiconductor die 102, as shown by a broken line.

Referring now to FIGS. 2, 2A and 2B of the drawings, one embodiment of a reinforcement structure for an RDL structure is shown. FOWLP 100′ comprises a semiconductor die 102 encapsulated in a molding compound 106, which also abuts one major surface MS1 of RDL structure 104′. Bond pads 108 of semiconductor die 102 are operably coupled to contacts 110, or, optionally, to surface traces (not shown), which extend to a first level of conductive traces 112 internal to RDL structure 104′. Interlayer contacts 120 operably mutually interconnect vertically adjacent or non-adjacent levels of conductive traces 112, through holes in intervening levels of low-k dielectric material 118, conductive traces 112 being ultimately coupled to external connections on the major surface MS2 of RDL structure 104′ opposing semiconductor die 102. As illustrated, but without limitation, the external connections may comprise solder balls (conductive elements 114) formed or placed on under bump metallization (UBM) surrounded by patterned solder stop 116, as is conventional. Also present in RDL structure 104′ is reinforcement structure 200, which is located adjacent to and within proximity to a peripheral edge P of RDL structure 104′.

Reinforcement structure 200 extends between the major surfaces MS1 and MS2 of RDL structure 104′, and is electrically isolated from the conductive traces 112 as well as contacts 110 and 120 and from peripheral edge P by intervening low-k dielectric material 118. Reinforcement structure 200 comprises levels of conductive material in the form of linear beams 212 connected vertically by intervening conductive connection elements in the form of columns comprising column elements 214 e. Viewed from the perspective of FIG. 2A, it can be seen that the beams 212 may extend laterally between adjacent column elements 214 e. As shown, beams 212 may be located proximate, and exposed on, each major surface MS1 and MS2 of RDL structure 104′. In another embodiment, beams 212 may be located below a level of low-k dielectric material 118 on each major surface MS1 and MS2 of RDL structure 104′, and the ends of column elements 214 e may be exposed. As shown in FIG. 2B, in lieu of continuous vertically extending columns comprising mutually superimposed column elements 214 e, column elements 214 e on different levels may be laterally offset from one another.

It will be appreciated that reinforcement structure 200 may be formed simultaneously with the remainder of RDL structure 104′, by appropriate blanket deposition of levels of conductive material and low-k dielectric material 118 layer by layer in conjunction with appropriate patterning and material removal, as known to those of ordinary skill in the art. Stated another way when, for example, a conductive trace 112 at a particular level is to be formed, blanket deposited conductive material, for example, copper or aluminum, may be masked and etched to not only form conductive traces 112 but also beams 212 at that level proximate periphery P. Similarly, if an interlayer contact 120 is to be formed by deposition of conductive material in a hole in a level of low-k dielectric material 118 alone or in conjunction with a conductive trace 112 over interlayer contact 120, another hole proximate periphery P and opening onto a preformed beam 212 may be simultaneously filled to form a column element 214 e. Likewise, with appropriate patterning a beam 212 may be formed simultaneously with a column element 214 e extending into a hole in a level of low-k dielectric material 118 below. Of course, beams 212 need not be formed on a same level as conductive traces 112 of a given level; instead, a column element 214 e may be formed at that level and an associated beam 212 formed at a level above or below the trace level, so that conductive traces 112 and beams 212 are vertically offset.

FIGS. 3A, 3B, 3C and 3D of the drawings illustrate another embodiment of an RDL structure 104″ according to the disclosure. In FIG. 3A, a schematic top elevation, a semiconductor die 102 is depicted in broken lines located on RDL structure 104″, and molding compound 106, encapsulating semiconductor die 102 and in contact with major surface MS1 of RDL structure 104″, has been omitted for clarity of illustration. As shown, a reinforcement structure 200′, as viewed from above, exhibits a continuous zig-zag structure Z approximating a square wave in form and comprising a pattern of linear beams 212 connected end-to-end, every other beam 212 being parallel to peripheral edge P of reinforcement structure 200′ with intervening beams 212 being perpendicular to peripheral edge P. As shown, beams 212 perpendicular to peripheral edge P may be longer than beams 212 parallel thereto; however, all beams may be of equal length, or beams 212 parallel to peripheral edge P may be longer than beams 212 perpendicular thereto. The beams 212 parallel to peripheral edge P and closest in proximity thereto may be located between about 5 μm to about 10 μm inward from peripheral edge P. As illustrated in FIG. 3B, reinforcement structure 200′ extends between the major surfaces MS1 and MS2 of RDL structure 104″, and is electrically isolated from the conductive traces 112 as well as contacts 110 and 120 and from peripheral edge P by intervening low-k dielectric material 118. Reinforcement structure 200′, like reinforcement structure 200, comprises levels of conductive material in the form of beams 212 connected vertically by intervening beams 212 at adjacent levels. Viewed from the perspective of FIG. 3B, it can be seen that portions of the beams 212 perpendicular to peripheral edge P extend laterally between beams 212 parallel to peripheral edge P and connecting adjacent levels of beams 212 perpendicular to peripheral edge P. As shown, beams 212 parallel to peripheral edge P may be located proximate, and exposed on, each major surface MS1 and MS2 of RDL structure 104″. In another embodiment, beams 212 parallel to peripheral edge P may be located below a level of low-k dielectric material 118 on each major surface MS1 and MS2 of RDL structure 104″, and beams 212 perpendicular to peripheral edge P may be exposed. As shown in FIG. 3B, column elements 214 e shown in broken lines, may, optionally, be located to extend between mutually vertically superimposed beams 212. Referring to FIG. 3C, in another implementation of reinforcement structure 200′, rather than various levels of alternating levels of beams 212 respectively perpendicular and parallel to peripheral edge P forming a zig-zag pattern, two or more different levels of beams 212 may instead follow opposite zig-zag patterns as depicted, respectively, in a solid line Z1 and a broken line Z2, wherein beams 212 perpendicular to peripheral edge P are vertically superimposed (broken line Z2 slightly offset for clarity) and beams 212 parallel to peripheral edge P are offset at different distances from peripheral edge P. Column elements 214 e (not shown in FIG. 3C) may extend between adjacent levels of superimposed beams 212. Referring to FIG. 3D, in a further implementation of reinforcement structure 200′, beams 212 on different levels both parallel and perpendicular to peripheral edge P may be offset parallel to peripheral edge P in a phase-shifted manner as depicted, respectively, in solid line Z1 and broken line Z2 (broken line slightly offset for clarity), and vertically superimposed beams 212 parallel to peripheral edge connected by interposed column elements 214 e, not shown in FIG. 3D. Of course, greater than two levels of beams 212 may be mutually offset in a phase-shifted manner.

It will be appreciated that reinforcement structure 200′, as in the case of reinforcement structure 200, may be formed simultaneously with the remainder of RDL structure 104″, by appropriate blanket deposition of levels of conductive material and low-k dielectric material 118 layer by layer in conjunction with appropriate patterning and material removal, as known to those of ordinary skill in the art, as described above with respect to reinforcement structure 200.

It will also be apparent to those of ordinary skill in the art that one or more levels of beams 212 may be configured in a zig-zag pattern, while other levels may be configured with all beams 212 lying parallel to a peripheral edge P of a reinforcement structure 200. Further, patterns other than zig-zag may be easily configured by appropriate patterning of conductive material, so that, for example, a continuous beam in a sinusoidal pattern may be formed, rather than a zig-zag pattern approximating a square wave.

In one embodiment, a redistribution layer (RDL) structure comprises at least one level of conductive traces between adjacent levels of low-k dielectric material and a reinforcement structure comprising conductive material proximate and inwardly of a periphery of the RDL structure, the reinforcement structure electrically isolated from the at least one level of conductive traces and extending between a first major surface and a second major surface of the RDL structure.

In another embodiment, a semiconductor device package comprises a semiconductor die, a redistribution layer (RDL) structure electrically connected on one major surface thereof to the semiconductor die, the RDL structure comprising one or more levels of conductive traces, at least some of the conductive traces extending laterally beyond a periphery of the semiconductor die, contacts electrically connected to the conductive traces defining a pattern for terminal pads on another, opposing major surface of the RDL structure, external conductive elements protruding from the terminal pads and reinforcement structure extending between the major surfaces of the RDL structure, comprising conductive material electrically isolated from the conductive traces and conductive contacts, and located peripherally inwardly of and adjacent edges of the RDL structure.

In a further embodiment, a method of fabricating a redistribution layer (RDL) structure comprises forming a level of low-k dielectric material with a selected periphery for an RDL structure, forming and patterning a level of conductive material on and extending into at least one hole in the level of low-k dielectric material to define conductive traces, at least one contact in communication with at least one conductive trace, and conductive elements of a reinforcement structure laterally separated and electrically isolated from the conductive traces adjacent the selected periphery. Another level of low-k dielectric material is formed over the patterned level of conductive material with holes to expose a portion of at least one conductive trace and one or more conductive elements of the reinforcement structure. Another level of conductive material is formed on and extending into at least one hole in the another level of low-k dielectric material to contact the exposed portion of the at least one conductive trace and the one or more conductive elements of the reinforcement structure and the level of conductive material is patterned to define conductive traces and conductive elements of the reinforcement structure laterally separated and electrically isolated from the conductive traces adjacent the selected periphery. A further level of low-k dielectric material is formed with holes to expose a portion of at least one conductive trace and one or more conductive elements of the reinforcement structure, and the holes in the further level of low-k dielectric material are filled with conductive material to form at least one contact in communication with the at least one conductive trace and one or more conductive elements of the reinforcement structure.

Embodiments of the disclosure provide a reinforcement structure to an RDL structure adjacent the periphery thereof and electrically isolated from conductive paths of the RDL structure. The reinforcement structure may mechanically interlock with low-k dielectric materials of the RDL structure and may prevent or reduce tendencies of these relatively fragile dielectric materials to delaminate, crack or otherwise degrade under thermal, mechanical or residual stresses by providing a robust, continuous, multilevel peripheral barrier to arrest crack propagation and/or redirect crack propagation through the low-k dielectric material in a non-detrimental direction. The extension of such a reinforcement structure, as disclosed, between opposing major surfaces of an RDL structure incorporating same may add structural rigidity to semiconductor device packages employing such RDL structures. Continuity and structural integrity of the reinforcement structure may be easily confirmed during electrical testing of the RDL structure conductive paths by contacting exposed portions of the conductive material of the reinforcement structures at various locations to detect shorting

While certain illustrative embodiments have been described in connection with the figures, those of ordinary skill in the art will recognize and appreciate that embodiments encompassed by the disclosure are not limited to those embodiments explicitly shown and described herein. Rather, many additions, deletions, and modifications to the embodiments described herein may be made without departing from the scope of embodiments encompassed by the disclosure, such as those hereinafter claimed, including legal equivalents. In addition, features from one disclosed embodiment may be combined with features of another disclosed embodiment while still being encompassed within the scope of the disclosure. 

What is claimed is:
 1. A redistribution layer (RDL) structure, comprising: at least one level of conductive traces between adjacent levels of a low-k dielectric material; and a reinforcement structure extending between a first major surface and a second major surface of the RDL structure and comprising conductive material configured as multiple levels of parallel beams, the multiple levels of parallel beams including a first beam including a top surface substantially planar with the first major surface of the RDL structure, a second beam including a bottom surface substantially planar with the second major surface of the RDL structure and at least one other beam between the first beam and the second beam, the multiple levels of parallel beams located proximate to and inward of a periphery of the RDL structure, adjacent beams interconnected by vertically extending column elements, the first beam and the second beam each having a lateral dimension that is greater than the lateral dimensions of the vertically extending column elements, the reinforcement structure electrically isolated from the at least one level of conductive traces.
 2. The RDL structure of claim 1, wherein the first beam and the second beam extend continuously within the periphery of the RDL structure.
 3. The RDL structure of claim 1, wherein the RDL structure comprises a same material as the at least one level of conductive traces, and further comprising conductive contacts extending between the at least one level of conductive traces and the first major surface and the second major surface.
 4. The RDL structure of claim 1, wherein the low-k dielectric material comprises a laminate of multiple levels of the low-k dielectric material.
 5. The RDL structure of claim 4, wherein the at least one level of conductive traces comprises two or more levels of conductive traces.
 6. The RDL structure of claim 5, wherein at least two conductive traces of different levels are interconnected with a conductive contact, and at least some of the at least two conductive traces are electrically connected to a contact extending to the first major surface and to another contact extending to the second major surface.
 7. The RDL structure of claim 1, wherein at least some of the vertically extending column elements are laterally offset from at least one other column element above or below.
 8. The RDL structure of claim 1, wherein the first beam, the second beam and the at least one other beam extend parallel to peripheral edges of the RDL structure to define a square wave pattern when viewed from a major surface of the RDL structure.
 9. The RDL structure of claim 1, wherein beams of different and adjacent levels are oriented perpendicularly to one and another to define a zig-zag pattern when viewed from a major surface of the RDL structure.
 10. The RDL structure of claim 5, wherein each level of the multiple levels of parallel beams extends continuously within and proximate to the periphery of the RDL structure.
 11. A semiconductor device package, comprising: a semiconductor die; a redistribution layer (RDL) structure electrically connected on a first major surface thereof to the semiconductor die, the RDL structure comprising: one or more levels of conductive traces, at least some of the one or more levels of conductive traces extending laterally beyond a periphery of the semiconductor die; contacts electrically connected to the one or more levels of conductive traces defining a pattern for terminal pads on a second major surface of the RDL structure; external conductive elements protruding from the terminal pads; and a reinforcement structure extending between the first major surface of the RDL structure and the second major surface of the RDL structure, the reinforcement structure comprising a conductive material configured as multiple levels of parallel beams including a first beam including a top surface substantially planar with the first major surface of the RDL structure, a second beam including a bottom surface substantially planar with the second major surface of the RDL structure, and at least one other beam between the first beam and the second beam, the multiple levels of parallel beams located proximate to and inward of a periphery of the RDL structure, the first beam being inward from the periphery by a first distance, the second beam being inward from the periphery by the first distance, adjacent beams interconnected by vertically extending column elements, the reinforcement structure electrically isolated from the one or more levels of conductive traces and conductive contacts.
 12. The semiconductor device package of claim 11, wherein the reinforcement structure comprises one of a square wave pattern extending parallel to each peripheral edge of the RDL structure, and a zig-zag pattern extending linearly and parallel to each peripheral edge of the RDL structure.
 13. The semiconductor device package of claim 11, wherein the multiple levels of parallel beams and the vertically extending column elements of the reinforcement structure comprise a number of interconnected levels equal to a number of levels of low-k dielectric material comprising a laminate dielectric of the RDL structure.
 14. The semiconductor device package of claim 13, wherein the number of interconnected levels of the reinforcement structure mechanically interlock with the number of levels of low-k dielectric material.
 15. The semiconductor device package of claim 11, further comprising a molded encapsulant surrounding at least sides of the semiconductor die, in contact with and bonded to the first major surface of the RDL structure and extending to peripheral edges thereof.
 16. The semiconductor device package of claim 11, wherein the reinforcement structure extends continuously inwardly of and proximate to peripheral edges of the RDL structure.
 17. The semiconductor device package of claim 11, configured as a fan-out wafer level package (FOWLP).
 18. A method of fabricating a redistribution layer (RDL) structure, the method comprising: forming a first level of low-k dielectric material with a periphery for an RDL structure; forming and patterning a first level of conductive material on and extending into at least one of first holes in the first level of low-k dielectric material to define: first conductive traces, at least one contact in communication with at least one of the first conductive traces, and a first beam of a reinforcement structure laterally separated and electrically isolated from the first conductive traces, the first beam adjacent to the periphery, the first beam including a surface substantially planar with a first major surface of the RDL structure; forming a second level of low-k dielectric material over the first level of conductive material with second holes to expose a portion of at least one of the first conductive traces and the first beam; forming a second level of conductive material on and extending into at least one of the second holes in the second level of low-k dielectric material to contact the exposed portion of the at least one of the first conductive traces and the first beam and patterning to define: second conductive traces, a second beam of the reinforcement structure laterally separated and electrically isolated from the second conductive traces, the second beam adjacent to the periphery, the second beam parallel to the first beam, and a first vertically-extending column of the reinforcement structure, the first vertically-extending column contacting the first beam and the second beam; forming a third level of low-k dielectric material with third holes to expose a portion of at least one intermediate conductive trace of an intermediate conductive layer and an intermediate beam of the reinforcement structure of the intermediate conductive layer, the intermediate conductive layer being beneath the third level of low-k dielectric material; and forming a third level of conductive material on and extending into at least one of the third holes in the third level of low-k dielectric material to contact the exposed portion of the at least one intermediate conductive trace and the intermediate beam, and patterning to define: third conductive traces, a third beam of the reinforcement structure laterally separated and electrically isolated from the third conductive traces, the third beam adjacent to the periphery, the third beam parallel to the first beam, the third beam including a surface substantially planar with a second major surface of the RDL structure, and a second vertically-extending column contacting the intermediate beam and the third beam, the first beam and the third beam each having a lateral dimension that is greater than the lateral dimensions of either of the first vertically-extending column and the second vertically-extending column.
 19. The method of claim 18, further comprising forming the first beam and the third beam of the reinforcement structure to extend proximate to and within the periphery to form a continuous peripheral structure.
 20. The method of claim 18, further comprising using a common conductive material for the at least one contact, the first, second, and intermediate conductive traces and the first beam, second beam, third beam, first vertically-extending column, and second vertically-extending column of the reinforcement structure.
 21. The method of claim 18, wherein forming and patterning the first, second, and third levels of low-k dielectric material comprises forming and patterning a photodefinable low-k dielectric material. 